<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        function fn1() {
            return new Promise((resolve, reject) => {
                setTimeout(() => {
                    console.log("第一步");
                    resolve();
                }, 1000);
            });
        }

        (async function() {
            await fn1();
            console.log("第二步");
        })();

        console.log("Hello");
    </script>
</body>
</html>